In general, a vacuum cleaner is an electric appliance that draws in and collects dust or dirt from a surface to be cleaned by using a suction force generated from a vacuum source. Various kinds of vacuum cleaners have been developed, one of which is a canister vacuum cleaner that is generally includes a cleaner body, a connecting unit and suction brush.
Installed in the cleaner body are a vacuum source, such as a suction motor, that generates a suction force and a dust separating part that collects drawn-in dust and/or dirt. The connecting unit includes a handle to be grasped by a user, an extended tube to connect the handle to the suction brush, and a flexible hose to connect the handle to the cleaner body. In addition, the suction brush, which is the portion that comes in contact with the surface to be cleaned and draws in air containing dust and/or dirt, has a suction opening formed in a bottom surface thereof.
As non-limiting examples of the types of surfaces that a vacuum cleaner may clean, there are a hard floors and a carpet. As used herein the term “hard floor” means a surface to be cleaned having a slippery surface made of stone, wood, or floor paper.
If the surface to be cleaned is a hard floor, the suction brush of the vacuum cleaner often sticks to the surface to be cleaned due to the suction force. In this case, a user must exert a large amount of force in handling the suction brush due to the suction brush sticking to the surface to be cleaned. The forces caused by sticking that must be overcome by a user are hereinafter referred to as “operation resistance.” By contrast, if the surface to be cleaned is a carpet, the number of times that the suction brush of the vacuum cleaner sticks to the surface to be cleaned is relatively less. When the surface to be cleaned is the carpet, however, a larger suction force is required to draw in dust or dirt from the fibers on the upper surface of the carpet as compared with when the surface to be cleaned is a hard floor.
The operation resistance and the suction force of the suction brush to the surface to be cleaned are closely connected with the height of the suction brush from the surface to be cleaned, i.e., the distance between the surface to be cleaned and the bottom surface of the suction brush in which the suction opening is formed. To be more specific, the smaller the distance between the surface to be cleaned and the bottom surface of the suction brush, the greater the suction force and the greater the operation resistance. Accordingly, the larger the distance between the surface to be cleaned and the bottom surface of the suction brush, the smaller the suction force and the smaller the operation resistance.
When the distance from the bottom surface of the suction brush to the surface to be cleaned is uniformly maintained, a large amount of force is constantly required in handling the suction brush if the surface to be cleaned is a hard floor because the operation resistance of the suction brush is large, and dust and/or dirt are not efficiently drawn in if the surface to be cleaned is a carpet because the suction force is small.
To address the problems described above, a suction brush in which the distance between the bottom surface thereof and the surface to be cleaned can be varied has been developed. In the developed suction brush, a lever, which is manually operated by the user, is exposed at an upper surface of the suction brush. Accordingly, if the surface to be cleaned is a hard floor, the user must manually manipulate the lever to move the bottom surface of the suction brush away from the surface to be cleaned, thereby increasing the distance therebetween and reducing the operation resistance of the suction brush. In addition, if the surface to be cleaned is a carpet, the user must manually manipulate the lever to move the bottom surface of the suction brush closer to the surface to be cleaned, thereby decreasing the distance therebetween and increasing the suction force of the suction brush.
Because the user must manually manipulate the lever of the suction brush whenever the surface to be cleaned is changed, the user is inconvenienced.